Determination of a user’s glycated hemoglobin level using pulse spectroscopy

Abstract

An electronic device comprises a housing configured to contact a user's skin, an optical transmitter array, an optical receiver, a memory element and a processing element. The optical transmitter array outputs a plurality of optical signals that pass through the user's skin, each of the plurality of optical signals having one of three wavelengths. The optical receiver receives the optical signals and generates corresponding photoplethysmogram (PPG) signals. The memory element stores absorption constants for deoxyhemoglobin blood content, oxyhemoglobin blood content and glycated hemoglobin blood content, each absorption constant associated with one of the first wavelength, the second wavelength or the third wavelength. The processing element determines a glycated hemoglobin blood level for the user based on a ratio of a determined glycated hemoglobin blood content to a sum of determined deoxyhemoglobin blood content, a determined oxyhemoglobin blood content and a determined glycated hemoglobin blood content.

What is claimed is: 
     
         1 . An electronic device, comprising:
 a housing including a bottom wall configured to contact a user's skin;   an optical transmitter array positioned at a first location on the bottom wall and operable to output a plurality of optical signals that pass through a user's skin, the plurality of optical signals including a first optical signal having a first wavelength, a second optical signal having a second wavelength and a third optical signal having a third wavelength;   an optical receiver positioned at a second location on the bottom wall and operable to receive the optical signals modulated by the skin of the user and generate first, second and third photoplethysmogram (PPG) signals resulting from the received first, the second and the third optical signals, respectively, the first optical signal, the second optical signal and the third optical signal each traveling substantially along the same path and each optical signal containing a cardiac component of the user;   a memory element configured to store absorption constants for deoxyhemoglobin blood content, oxyhemoglobin blood content and glycated hemoglobin blood content, each absorption constant associated with one of the first wavelength, the second wavelength or the third wavelength; and   a processing element in electronic communication with the optical transmitter array and the optical receiver, the processing element configured to:
 receive the first, the second and the third PPG signals from the optical receiver, 
 determine a first AC-to-DC ratio for the first PPG signal, 
 determine a second AC-to-DC ratio for the second PPG signal, 
 determine a third AC-to-DC ratio for the third PPG signal, 
 determine, based on the three determined AC-to-DC ratios, the deoxyhemoglobin blood content, the oxyhemoglobin blood content and the glycated hemoglobin blood content, and 
 determine a glycated hemoglobin blood level for the user based on a ratio of the determined glycated hemoglobin blood content to a sum of the determined the deoxyhemoglobin blood content, the determined oxyhemoglobin blood content and the determined glycated hemoglobin blood content. 
   
     
     
         2 . The electronic device of  claim 1 , wherein the processing element is further configured to:
 determine a fourth AC-to-DC ratio associated with deoxyhemoglobin blood content, a first absorption constant for deoxyhemoglobin blood content corresponding to the first wavelength, oxyhemoglobin blood content, a first absorption constant for oxyhemoglobin blood content corresponding to the first wavelength, glycated hemoglobin blood content, and a first absorption constant for glycated blood content corresponding to the first wavelength,   determine a fifth AC-to-DC ratio associated with deoxyhemoglobin blood content, a second absorption constant for deoxyhemoglobin blood content corresponding to the second wavelength, oxyhemoglobin blood content, a second absorption constant for oxyhemoglobin blood content corresponding to the second wavelength, glycated hemoglobin blood content, and a second absorption constant for glycated blood content corresponding to the second wavelength,   determine a sixth AC-to-DC ratio associated with deoxyhemoglobin blood content, a third absorption constant for deoxyhemoglobin blood content corresponding to the third wavelength, oxyhemoglobin blood content, a third absorption constant for oxyhemoglobin blood content corresponding to the third wavelength, glycated hemoglobin blood content, and a third absorption constant for glycated blood content corresponding to the third wavelength, and   determine, based on the six determined AC-to-DC ratios, the deoxyhemoglobin blood content, the oxyhemoglobin blood content and the glycated hemoglobin blood content.   
     
     
         3 . The electronic device of  claim 1 , wherein the memory element is further configured to store a plurality of signal path factors, the plurality of signal path factors including a first signal path factor corresponding to the first wavelength, a second signal path factor corresponding to the second wavelength, and a third signal path factor corresponding to the third wavelength. 
     
     
         4 . The electronic device of  claim 3 , wherein the processing element is further configured to determine the first AC-to-DC ratio for the first PPG signal based on the first signal path factor, determine the second AC-to-DC ratio for the second PPG signal based on the second signal path factor, and determine a third AC-to-DC ratio for the third PPG signal based on the third signal path factor. 
     
     
         5 . The electronic device of  claim 1 , wherein the optical transmitter array includes a first optical transmitter configured to transmit the first optical signal, a second optical transmitter configured to transmit the second optical signal and a third optical transmitter configured to transmit the third optical signal, and wherein the processing element is further configured to control the first optical transmitter to transmit the first optical signal during a first period of time, the second optical transmitter to transmit the second optical signal during a second period of time and the third optical transmitter to transmit the third optical signal during a third period of time. 
     
     
         6 . The electronic device of  claim 1 , wherein the processing element is further configured to control the optical transmitter array to transmit the first optical signal during a first period of time, the optical transmitter array to transmit the second optical signal during a second period of time and the optical transmitter array to transmit the third optical signal during a third period of time. 
     
     
         7 . The electronic device of  claim 6 , wherein the first period of time, the second period of time and the third period of time are in sequential order. 
     
     
         8 . The electronic device of  claim 6 , wherein the processing element is further configured to control the optical transmitter array to cause the first optical transmitter to transmit the first optical signal, the second optical signal and the third optical signal during a first period of time. 
     
     
         9 . The electronic device of  claim 6 , wherein the optical transmitter array includes a first optical transmitter configured to transmit the first optical signal, the second optical signal and the third optical signal. 
     
     
         10 . The electronic device of  claim 6 , wherein the optical transmitter array includes a first optical transmitter configured to transmit the first optical signal, a second optical transmitter configured to transmit the second optical signal and a third optical transmitter configured to transmit the third optical signal. 
     
     
         11 . The electronic device of  claim 1 , wherein the first wavelength is between 620-650 nm and the second wavelength is between 650-700 nm. 
     
     
         12 . The electronic device of  claim 11 , wherein the third wavelength is between one of 760 nm-860 nm and 900 nm-1,000 nm. 
     
     
         13 . The electronic device of  claim 1 , further comprising a band, wherein the housing and band secure the electronic device to an extremity of the user. 
     
     
         14 . An electronic device, comprising:
 a housing including a bottom wall configured to contact a user's skin;   an optical transmitter array positioned at a first location on the bottom wall and operable to output a plurality of optical signals that pass through a user's skin, the plurality of optical signals including a first optical signal having a first wavelength, a second optical signal having a second wavelength and a third optical signal having a third wavelength;   an optical receiver positioned at a second location on the bottom wall and operable to receive the optical signals modulated by the skin of the user and generate first, second and third photoplethysmogram (PPG) signals resulting from the received first, the second and the third optical signals, respectively, the first optical signal, the second optical signal and the third optical signal each traveling substantially along the same path and each optical signal containing a cardiac component of the user;   a memory element configured to store absorption constants for deoxyhemoglobin blood content, oxyhemoglobin blood content and glycated hemoglobin blood content, each absorption constant associated with one of the first wavelength, the second wavelength or the third wavelength; and   a processing element in electronic communication with the optical transmitter array and the optical receiver, the processing element configured to:
 receive the first, the second and the third PPG signals from the optical receiver, 
 determine a first AC-to-DC ratio for the first PPG signal, 
 determine a second AC-to-DC ratio for the second PPG signal, 
 determine a third AC-to-DC ratio for the third PPG signal, 
 determine a fourth AC-to-DC ratio associated with deoxyhemoglobin blood content, a first absorption constant for deoxyhemoglobin blood content corresponding to the first wavelength, 
 oxyhemoglobin blood content, a first absorption constant for oxyhemoglobin blood content corresponding to the first wavelength, glycated hemoglobin blood content, and a first absorption constant for glycated blood content corresponding to the first wavelength, 
 determine a fifth AC-to-DC ratio associated with deoxyhemoglobin blood content, a second absorption constant for deoxyhemoglobin blood content corresponding to the second wavelength, oxyhemoglobin blood content, a second absorption constant for oxyhemoglobin blood content corresponding to the second wavelength, glycated hemoglobin blood content, and a second absorption constant for glycated blood content corresponding to the second wavelength, 
 determine a sixth AC-to-DC ratio associated with deoxyhemoglobin blood content, a third absorption constant for deoxyhemoglobin blood content corresponding to the third wavelength, oxyhemoglobin blood content, a third absorption constant for oxyhemoglobin blood content corresponding to the third wavelength, glycated hemoglobin blood content, and a third absorption constant for glycated blood content corresponding to the third wavelength, 
 determine, based on the six determined AC-to-DC ratios, the deoxyhemoglobin blood content, the oxyhemoglobin blood content and the glycated hemoglobin blood content, and 
 determine a glycated hemoglobin blood level for the user based on a ratio of the determined glycated hemoglobin blood content to a sum of the determined the deoxyhemoglobin blood content, the determined oxyhemoglobin blood content and the determined glycated hemoglobin blood content. 
   
     
     
         15 . The electronic device of  claim 14 , wherein the memory element is further configured to store a plurality of signal path factors, the plurality of signal path factors including a first signal path factor corresponding to the first wavelength, a second signal path factor corresponding to the second wavelength, and a third signal path factor corresponding to the third wavelength, and wherein the processing element is further configured to:
 determine the first AC-to-DC ratio for the first PPG signal based on the first signal path factor,   determine the second AC-to-DC ratio for the second PPG signal based on the second signal path factor, and   determine a third AC-to-DC ratio for the third PPG signal based on the third signal path factor.   
     
     
         16 . The electronic device of  claim 14 , further comprising a band, wherein the housing and band secure the electronic device to an extremity of the user, and wherein the first wavelength is between 620-650 nm and the second wavelength is between 650-700 nm. 
     
     
         17 . An electronic device, comprising:
 a housing including a bottom wall configured to contact a user's skin;   an optical transmitter array positioned at a first location on the bottom wall and operable to output a plurality of optical signals that pass through a user's skin, the plurality of optical signals including a first optical signal having a first wavelength, a second optical signal having a second wavelength and a third optical signal having a third wavelength;   an optical receiver positioned at a second location on the bottom wall and operable to receive the optical signals modulated by the skin of the user and generate first, second and third photoplethysmogram (PPG) signals resulting from the received first, the second and the third optical signals, respectively, the first optical signal, the second optical signal and the third optical signal each traveling substantially along the same path and each optical signal containing a cardiac component of the user;   a memory element configured to store:
 absorption constants for deoxyhemoglobin blood content, oxyhemoglobin blood content and glycated hemoglobin blood content, each absorption constant associated with one of the first wavelength, the second wavelength or the third wavelength, and 
 a plurality of signal path factors, the plurality of signal path factors including a first signal path factor corresponding to the first wavelength, a second signal path factor corresponding to the second wavelength, and a third signal path factor corresponding to the third wavelength; and 
   a processing element in electronic communication with the optical transmitter array and the optical receiver, the processing element configured to:
 receive the first, the second and the third PPG signals from the optical receiver, 
 determine a first AC-to-DC ratio for the first PPG signal based on the first signal path factor, 
 determine a second AC-to-DC ratio for the second PPG signal based on the second signal path factor, 
 determine a third AC-to-DC ratio for the third PPG signal based on the third signal path factor, 
 determine, based on the three determined AC-to-DC ratios, the deoxyhemoglobin blood content, the oxyhemoglobin blood content and the glycated hemoglobin blood content, and 
 determine a glycated hemoglobin blood level for the user based on a ratio of the determined glycated hemoglobin blood content to a sum of the determined the deoxyhemoglobin blood content, the determined oxyhemoglobin blood content and the determined glycated hemoglobin blood content. 
   
     
     
         18 . The electronic device of  claim 17 , wherein the processing element is further configured to:
 determine a fourth AC-to-DC ratio associated with deoxyhemoglobin blood content, a first absorption constant for deoxyhemoglobin blood content corresponding to the first wavelength, oxyhemoglobin blood content, a first absorption constant for oxyhemoglobin blood content corresponding to the first wavelength, glycated hemoglobin blood content, and a first absorption constant for glycated blood content corresponding to the first wavelength,   determine a fifth AC-to-DC ratio associated with deoxyhemoglobin blood content, a second absorption constant for deoxyhemoglobin blood content corresponding to the second wavelength, oxyhemoglobin blood content, a second absorption constant for oxyhemoglobin blood content corresponding to the second wavelength, glycated hemoglobin blood content, and a second absorption constant for glycated blood content corresponding to the second wavelength,   determine a sixth AC-to-DC ratio associated with deoxyhemoglobin blood content, a third absorption constant for deoxyhemoglobin blood content corresponding to the third wavelength, oxyhemoglobin blood content, a third absorption constant for oxyhemoglobin blood content corresponding to the third wavelength, glycated hemoglobin blood content, and a third absorption constant for glycated blood content corresponding to the third wavelength, and   determine, based on the six determined AC-to-DC ratios, the deoxyhemoglobin blood content, the oxyhemoglobin blood content and the glycated hemoglobin blood content.   
     
     
         19 . The electronic device of  claim 17 , wherein the processing element is further configured to determine the first signal path factor, the second signal path factor and the third signal path factor to account for differences in the substantially the same signal paths between the optical transmitter array and the optical receiver, the differences including a region of the user's skin each of the first optical signal, the second optical signal and the third optical signal pass based on the first wavelength, the second wavelength or the third wavelength, respectively. 
     
     
         20 . The electronic device of  claim 18 , wherein the first wavelength is between 620-650 nm, the second wavelength is between 650-700 nm and the third wavelength is between 900 nm-1,000 nm.